When a semiconductor device such as a metal-oxide-semiconductor field-effect transistor (MOSFET) is scaled down through various technology nodes, several techniques have been employed to improve device performance. One technique is a high-k (HK) dielectric material and metal gate (MG) scheme. Another example is to use a strained-semiconductor substrate. In implementing a HK/MG scheme, it is important to properly scale an equivalent oxide thickness (EOT), such as by using oxygen scavenging metal technique. Such techniques use a high temperature process to trigger the oxygen scavenging effect. It is desired to provide additional improvements to such techniques.